Director, Sense About Science USA, which advocates for an evidence based approach to science and technology and for clinical trial transparency. Editor, STATS.org, a collaboration between the American Statistical Association and Sense About Science USA. Visiting Fellow, Cornell University. I have written about data and statistics and how they are interpreted in our so-called "knowledge economy," especially in relation to risk and regulation. I've written for the New Yorker online, Harvard Business Review, The Financial Times, The Wall Street Journal, and many other publications. I speak regularly about the media's coverage of science and statistics and scientific communication. Educated at Trinity College Dublin, Georgetown, and Columbia.

Will Moderate Drinking Rot Your Brain?

It’s hard out there for a rat, especially if you’re inside a lab. No other species is prodded, discombobulated, or poisoned quite so much in the quest to protect humans, except mice. Take new research from Stanford University, just published in Nature Neuroscience. “Scientists stop rats stroke induced seizures with pulse of light,” says the headline on Stanford’s School of Medicine news page. It’s quite an amazing study, ingenious and insightful, a new, unexpected building block in our foundation of neural knowledge, which, one day, might play a distinct and important role in treating epilepsy.

Of course, first, the rats had to have strokes…

But when it came to researchers at Rutgers University testing the hypothesis that moderate to high drinking might cause changes in the brain, the inevitably grim final act of experimentation – the rats were killed and had their brains turned into microscope friendly hippocampus Carpaccio – was at least preceded by two weeks of boozing. If life in a lab is to be nasty, brutish and short, the critters at least preceded their fate with some degree of pleasure. The conclusion? At first glance, it appears that they died in the service of telling us something we really didn’t want to know – as The Atlantic.com put it, “Even ‘Moderate’ Drinking Impairs Brain Cell Formation.”

Britain’s Daily Mail – one of the most visited news sites in the world – was even more alarming: “Just two glasses of wine a day can nearly halve the number of brain cells we produce” ran the headline.

Except, there is more to the alcohol intake than at first seems evident. The rats were fed a liquid diet containing alcohol for two weeks, and then had blood extracted on their final night of drinking. When analyzed, the mean blood alcohol content was 0.08 percent, which is the legal driving limit. This was associated with a significant decrease in cell production – neurogenesis – in the hippocampus. Ergo, the researchers concluded, “moderate alcohol consumption over a period of 2 weeks” decreased production of neurons, which “are presumably beneficial for brain health.” No effect in motor function was detected, however.

From this, they concluded that “the relatively large magnitude of this effect indicates that even socially acceptable levels of alcohol consumption can have long-lasting and detrimental consequences for brain health and its structural integrity.”

Leaving aside the question of how one may go from a decrease in the production of cells “presumably” beneficial to brain health to a conclusion that socially acceptable drinking “can have long-lasting and detrimental consequences,” there is the more fundamental issue of whether the rats were engaged in the human equivalent of “socially acceptable” drinking to begin with.

“This is not moderate alcohol, but binge drinking,” says Fulton Crews, Director, of the Bowles Center for Alcohol Studies at the UNC Chapel Hill’s School of Medicine. He explains that as the National Institute of Alcohol Addiction and Alcoholism defines binge drinking as consuming five drinks for a male and four for a female in two hours, and as that achieves a blood alcohol content (BAC) equivalent to the legal driving limit, these rats were binging. For two weeks straight.

Remember, 0.08 percent was the rats’ blood alcohol content at the end of two weeks. They drank daily, throughout the night, and the Rutgers researchers note they probably had “higher [BAC] levels during some periods in time.” As Crews notes, we know that binge drinking inhibits neurogenesis.

One way to think about this “moderate drinking” in human terms is to ask what it would take to get a 180-pound man to a 0.08 BAC and keep him there for 10 hours. On waking, he’d need to down four or five drinks, and then a further drink every hour or so to stay topped up.

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